Two days into testimony over an appeal of the state Department of Environmental Protection’s approval of a natural gas compressor station in Weymouth, some witnesses have raised concern about the safety of the station’s expected emissions, while others testified that any toxins released would be within safety limits.

The DEP issued an air quality permit for the project in January, allowing the project to move forward. Opponents of the compressor station filed an appeal, which is what’s being considered in this week's hearings.

Compressor stations increase the pressure of natural gas in pipelines, speeding the movement of the gas so it can travel further. Enbridge, the company that plans to build the station, says this project would provide extra capacity on its Algonquin Gas Transmission and Maritimes & Northeast Pipeline systems to move natural gas into New England and on to markets in the Canadian Maritime provinces.

Some of the project's opponents rallied in Downtown Crossing outside the DEP offices as the hearings were underway Wednesday afternoon.

“It’s siting a toxic and explosive facility in the middle of a densely populated area, adjacent to critical infrastructure like the new Fore River Bridge and MWRA sewage pumping station," said Reverend Betsy Sowers. “Also, over 900 homes, schools, children. It’s in a flood zone. There are so many reasons not to put it there.”

Opponents also object to the expansion of fossil fuel infrastructure because of its contribution to climate change, although that has not been an issue in this week’s DEP hearings.

The group Greater Boston Physicians for Social Responsibility issued a report earlier in the week saying the surrounding area is already polluted and has an elevated cancer risk. Dr. Brita Lundberg of the group said at Wednesday's protest that she hasn't heard Gov. Charlie Baker speak of plans to address that.

"All I’ve heard is that he plans to put in a compressor station that will emit further carcinogens that are known to increase rates," Lundberg said. "That is just morally repugnant.”

Read more: The Fight Against A Gas Line Project In Weymouth Is Fought Every Day In Charlie Baker's Lobby

Philip Landrigan, the director of Boston College's Global Observatory on Pollution and Health testified Wednesday that DEP hasn't considered the existing contamination of the community, as they have in prior decisions like this.

"I don't think you should allow any additional benzene into this already polluted environment if your goal is to protect human health, and not to protect some other interest," Landrigan said.

(Read Philip Landrigan's written testimony.)

Boston University professor Nathan Phillips testified Wednesday that state models of the expected emissions from the project have been improperly influenced by Enbridge. Phillips suggested the state's support for the project is influenced by campaign donations to Baker.

"He gets money from Enbridge, from Eversource, National Grid," Phillips said. "Those are all co-investors in the Weymouth compressor station. So yeah, I believe there's conflicts of interest throughout this entire process."

An attorney for the DEP made a point of getting Phillips to clarify that he wasn't alleging any DEP employees financially benefited from approving permits for the project.

After the initial publication of this article, a spokesman from Eversource contacted WGBH News to object to Phillips' characterization of Eversource in this story's quote of his testimony.

"To be clear, we do not have, nor have we ever had, ownership interest in Atlantic Bridge which is the project behind the Weymouth compressor," spokesman Reid Lamberty wrote in an email. "We are also not investors in the project."

The utility did, however, invest in a prior project that included the compressor station.

The compressor station is currently part of the Atlantic Bridge project, which is owned by Algonquin Gas Transmission, LLC. Eversource previously held a 40 percent "Class B Sharing Ratio" ownership of Algonquin Gas Transmission, LLC.

Lamberty emphasized that the utility's prior ownership stake in Algonquin Gas LLC was limited specifically to the now defunct Access Northeast natural gas pipeline expansion project. That project was abandoned after courts and regulators would not allow the bill for the project to be picked up by utility customers.

But the Access Northeast project did include the Weymouth Compressor station as a component.

"That project may have expanded the Weymouth compressor station after it was built, but we have discontinued our participation in Access Northeast and the project is no longer under review," Lamberty wrote in his email.

In 2018, Eversource wrote off a more than $30 million investment in the Access Northeast project.

So while Eversource may not currently be an investor in the Weymouth gas compressor project, as Phillips stated in his testimony, the utility was an investor in a prior project that included the station.

Baker has repeatedly said objections directed at the state are misplaced. He told a WGBH News reporter on Monday that he's receptive to complaints about the project, but that they really should be directed to federal authorities who that have ultimate say.

(Read Nathan Phillips' written testimony.)

Nathan Phillips testifies
Nathan Phillips of Boston University (center, in front of microphone) testifies on Wednesday.

"People who have issues with the site, they should absolutely file those and we'll include those as part of the record and we'll get a serious review," Baker said.

Phillips also alleged there was improper collaboration between Enbridge and its regulators, citing reporting by the independent DeSmogBlog, which found emails through Freedom of Information requests that showed the DEP allowed Enbridge to view and edit its approval of the air quality permit before it was issued and "coached" the DEP on models for measuring the compressor station's emissions.

"So they were clearly collaborating together, working together on this model. And that's not OK," Phillips testified. "That's a conflict of interest."

DeSmogBlog also reported that the health impact assessment on the project ordered by Baker did not include test results from samples of the current air at the site that the DEP sent to a lab in Rhode Island. Those results showed the presence of several carcinogenic compounds.

Thursday’s testimony began with air compliance specialist John Hinckley, who reviewed the DEP approval for the town of Weymouth. The town opposes the construction of the compressor station. Hinckley testified that the station would exceed state guidelines for formaldehyde emissions. He said the modeling of toxic emissions conducted by Enbridge did not account for emissions when the station's turbine starts up.

"The start-up emissions are significantly higher than normal operations," Hinckley said in his testimony. "So it's a big slug of air pollution that goes into the air, roughly speaking, in one hour. Start-up emissions, I want to say, are about over 400 times higher than normal operation."

(Read John Hinckley's written testimony.)

Harvard University epidemiologist Douglas Dockery testified that those emissions, on top of existing pollution in the area, would present an unacceptable cancer risk. Dockery replied to attorneys for Enbridge, who compared the risk from the contaminants to those from smoking.

"There is a very big difference between exposures we put on ourselves versus exposures that are imposed on us without our control," Dockery said.

(Read Douglas Dockery's written testimony.)

Dockery also testified that Enbridge incorrectly accounted for the impact the site's proximity to the shore would have on the height of exhaust plumes from the compressor.

On Thursday afternoon, Enbridge began calling its own witnesses to testify in defense of the the compressor station and the DEP's approval of its air quality permit.

The first was Robert O'Neal, an expert in evaluating sound levels who was hired by Algonquin Gas Transmission, which is owned by Enbridge. O'Neal acknowledged that under state regulations, excessive noise levels could constitute air pollution, but that the noise at the compressor station would not reach that level.

(Read Robert O'Neal's written testimony.)

Consultant Peter Valberg also testified on behalf of Algonquin Gas Transmission, and explained the basis for the limits the DEP has set for toxic air emissions. Valberg read from his written testimony, saying that benzene and formaldehyde already measured in the atmosphere around the proposed site and the cancer risks associated with the air quality “in the Fore River Basin area fall within US EPA’s acceptable cancer risk range, meaning that these hypothetical cancer risks should not be viewed as providing evidence of unacceptable existing air quality.”

(Read Peter Valberg's written testimony.)

Peter Valberg testifies
Consultant Peter Valberg testified on behalf of Algonquin Gas Transmission Thursday.
Craig LeMoult WGBH

Attorneys for the group appealing the plan sought to discredit Valberg and his testimony, pointing to a case in which he published a paper arguing mesothelioma could be caused by smoking, contradicting scientific consensus on the subject. Valberg acknowledged in his testimony that he was asked to write the paper by attorneys representing a company that was being sued for exposing a worker to asbestos, which was known to cause mesothelioma. He also acknowledged the company funded his research.

The hearings continue Friday, with more Enbridge witnesses slated to testify.

This story has been updated to clarify the extent of Eversource's involvement in the gas compressor station project.